1. Field of the Invention
The present invention relates to a method of detecting the pinching of an object in a power window device, and more particularly, to a method of detecting the pinching of an object in a power window device and for reducing a detection error which arises when a motor torque value is increased at a time it is detected whether an object, which is pinched in a window, is present or absent in each of a plurality of travel regions, which are obtained by dividing the entire moving range of the window, and by comparing a motor torque value with a corrected base value.
2. Description of the Related Art
Conventionally, in power window devices used to open and close a window of a vehicle, an object may be pinched in the window particularly when the window is being moved in a closing direction. When the object is pinched in the window, a large force is applied to the object by a drive force in a window closing direction, by which an excessive load is applied to a window open/close motor which provides the window with the drive force.
To avoid the occurrence of such an undesirable situation, there has been proposed a power window device provided with a means, which detects an object pinched in a window when the window is opened and closed and instantly stops or reverses the drive of a window open/close motor when it is detected that the object is pinched to thereby prevent an excessive load from being applied to the motor. That is, there has been proposed a power window device for detecting an object pinched in a window.
In this case, while there have been proposed various types of power window devices for detecting an object pinched therein, there is a power window device for detecting an object pinched therein as disclosed the applicant of in U.S. Pat. No. 6,034,495.
FIG. 6 is a block diagram showing the arrangement of the main portion of the power window device for detecting a pinched object according to the above referenced patent.
As shown in FIG. 6, the power window device includes a window open/close manual switch 71, a micro control unit (MCU) 72, a motor drive unit 73, a window open/close motor 74, and a pulse generator 75. In this case, the window open/close manual switch 71 includes a plurality of switches, for example, a window raising switch (UP) 711, a window lowering switch (DOWN) 712, and an auto switch (AUTO) 713. The micro control unit (MCU) 72 includes a control/arithmetic operation unit 721, a RAM 722 and a pulse edge counter 723.
The window raising switch 711, the window lowering switch 712, and the auto switch 713 are connected to the input of the control/arithmetic operation unit 721, the output of the control/arithmetic operation unit 721 is connected to the input of the motor drive unit 73, and the output of the motor drive unit 73 is connected to the motor 74. The pulse generator 75 is directly coupled with the motor 74. The output of the pulse generator 75 is connected to the input of the pulse edge counter 723, and the output of the pulse edge counter 723 is connected to the control/arithmetic operation unit 721. The RAM 722 and the control/arithmetic operation unit 721 are connected to each other.
Further, FIG. 7 is a characteristic view showing an example of the base median values and the base values of the motor torque set to the respective travel regions of a window when the entire travel region thereof is divided into 36 travel regions in the power window device shown in FIG. 6, and FIG. 8 is a characteristic view showing an example of the corrected base values set to a part of the travel region in the power window device shown in FIG. 6.
In FIG. 7, an abscissa represents the number of arrival pieces of pulse edge interval data which are obtained by counting a piece of pulse edge interval data each time it arrives, and an ordinate represents motor torque. In the figure, M represents a motor torque value, A represents a base median value, K represents a base value, H represents a motor torque value when an object is pinched a moment after a window starts movement.
As shown in FIG. 7, the proposed power window device mentioned above is arranged such that 36 travel regions are formed by equally dividing the entire travel extent of the window, that is, the window movable region from a window full-open position to a window full-close position, and various types of values for determining the presence and absence of an object pinched in the window, that is, a base median value, a corrected base median value, a base value and a corrected base value are set to each of the travel regions as described below. In this case, the 36 regions are formed by generating 2-phase pulses from the pulse generator 75 when the motor 74 is in rotation, detecting the respective pulse edge intervals of the 2-phase pulses by the pulse edge counter 723 which counts clock signals and using the thus detected count values.
The outline of the operation of the power window device for detecting an object pinched therein shown in FIG. 6 will be described here using FIGS. 7 and 8 in combination.
When any switch of the window open/close manual switch 71 is manually operated, the micro control unit 72 outputs a drive signal corresponding to the manually operated switch to the motor drive unit 73 in response to the manual operation of the switch. The motor drive unit 73 supplies a motor drive signal to the motor 74 in response to the drive signal supplied thereto, rotates the motor 74 in one direction or the other direction in correspondence to the manually operated switch and causes the window coupled with the motor 74 to move in a window opening or closing direction by the rotation of the motor 74. The rotation of the motor causes the pulse generator 75 directly coupled with the motor 74 to be operated, by which 2-phase pulses each having a cycle corresponding to the rotation of the motor 74 are output from the pulse generator 75 and supplied to the edge counter 723. In this case, each of the 2-phase pulses is a square wave pulse having a 90xc2x0 phase difference and one cycle of which corresponds to one rotation of the motor 74. The pulse edge counter 723 detects timing at which each pulse edge of the supplied 2-phase pulses arrives and calculates an interval from a time at which one pulse arrives to a time at which a next pulse arrives by counting clock signals, and the control/arithmetic operation unit 721 detects a motor torque value based on the calculated count value.
In this case, the RAM 722 is provided with a base median value storing area, a base tolerance value storing area, a motor torque data addition value storing area, a start cancel storing area, the number of motor torque data in travel region storing area, the total number of motor torque data storing area, and the like. Then, the control/arithmetic operation unit 721 calculates the base median value A (for example, A0 to A4) of motor torque, the corrected base median value B (for example, B0 to B4) representing the average of motor torque values, the base value K (for example, K1 to K4) which is obtained by adding a given allowable base value to the base median value A (for example, A0 to A4), a correction coefficient (for example, xcex10 to xcex13) for correcting the base value K (for example, K1 to K4), and the corrected base value C (for example, C1 to C4), based on various kinds of data stored in these storing areas as shown in FIG. 8.
The example shown in FIG. 8 is a case in which the motor 74 is started when the window is located in a travel region N0 and the window is sequentially moved thereby from the travel region N0 in the directions of a travel region N1, a travel region N2, a travel region N3, and a travel region N4. A rate of change xcex11 represents the ratio (B0/A0) of the corrected base median value B0 obtained in the first travel region N0 to the base median value A0 set to the travel region N0; a rate of change xcex12 represents the ratio (B1/A1) of the corrected base median value B1 obtained in the next travel region N1 to the base median value A1 set to the travel region N1; a rate of change xcex13 represents the ratio (B2/A2) of the corrected base median value B2 obtained in the next travel region N2 to the base median value A2 set to the travel region N2; and a rate of change xcex14 represents the ratio (B3/A3) of the corrected base median value B3 obtained in the next travel region N3 to the base median value A3 set to the travel region N3. When it is supposed that the base value is represented by K, the corrected base value C1 of the travel region N1 is K1xc3x97xcex10 which is obtained by multiplying the rate of change xcex11 obtained in the travel region N0 by the base value K1 (A1+K) set to the travel region N1. In the same way, the corrected base value C2 of the travel region N2 is K2xc3x97xcex11 (K2 is the base value set to the travel region N2); the corrected base value C3 of the travel region N3 is K3xc3x97xcex12 (K3 is the base value set to the travel region N3); and the corrected base value C4 of the travel region N4 is K4xc3x97xcex13 (K4 is the base value set to the travel region N4).
The control/arithmetic operation unit 721 detects the motor torque values M when the window moves in the respective travel regions N1 to N4, compares the detected motor torque values M with the corrected base values C1 to C4 set to the travel regions N1 to N4. When the motor torque values exceed the corrected base values C1 to C4, the control/arithmetic operation unit 721 determines that an object is pinched in the window, instantly stops or reverses the drive of the motor 74 through the motor drive unit to thereby prevent the object pinched in the window from being damaged as well as prevent an excessive load from being applied to the motor 74.
The power window device according to the above proposal for detecting an object pinched therein sets the corrected base values, which are obtained by multiplying the base values K1 to K4 by the rates of change xcex11 to xcex13, to the travel regions N1 to N4, respectively, compares the motor torque values M detected in the respective travel regions N1 to N4 with the corrected base values C1 to C4 corresponding thereto and determines that the object is pinched in the window when the motor torque values M exceed the corrected base values C1 to C4. Accordingly, the proposed power window device can determine the presence or absence of the occurrence of an object pinched in the window in a state which can be adapted to the change of the motor torque values M when the window travels as compared with other conventionally known power window devices which determine that an object is pinched in a window when detected motor torque values M exceed base values K1 to K4 which correspond thereto in the comparison therebetween.
However, in the proposed power window device for detecting a pinched object, the corrected base values C1 to C4 set to the respective travel regions N1 to N4 are set to given values in the respective travel regions N1 to N4. Thus, when a motor torque value M is considerably greatly changed in a travel region, in particular, when an object is pinched in the window and when the window arrives a full-open position or a full-close position and a load applied to the window open/close motor 74 is greatly changed, there is caused a large dispersion in the result of comparison between a certain part and other part in the respective travel regions N1 to N4 when the detected motor torque values M are compared with the corrected base values C1 to C4 which are set to the given values in the respective travel regions N1 to N4. As a result, it is difficult to detect an object pinched in the window in a state in which the change of the motor torque values M is correctly followed, that is, it is difficult to greatly improve the detecting accuracy.
Accordingly, an object of the present invention, which was made in view of the above technical background, is to provide a method of detecting pinching of an object in a power window device capable of detecting the occurrence of an object pinched in a window with high detecting accuracy by changing corrected base values set in respective travel regions therein.
To achieve the above object, in a method of detecting pinching of an object in a power window device according to the present invention in which the entire travel region of the window is divided into a plurality of travel regions, a base median value, a base tolerance value, and a base value obtained by adding the base median value and the base tolerance value are set to each of the travel regions, the micro control unit includes means for finding a corrected base median value, which represents the average of the detected motor torque values, for finding a rate of change by dividing the found corrected base median value by a corresponding base median value, for calculating a correction coefficient based on the found rate of change, for finding a corrected base value by multiplying the calculated correction coefficient by the corresponding base value, for utilizing the found corrected base value as the corrected base value of the middle point of a corresponding travel region as well as for setting a corrected base line by connecting the corrected base values of the middle points of adjacent travel regions by a straight line, and for determining the presence or absence of the object pinched in the window by comparing the corrected base line with the detected motor torque value in each travel region.
As a preferred example in the above means, the corrected base value in the method of detecting pinching of an object in the power window device of the present invention is calculated by the average of the correction coefficient and the rate of change found in an immediately preceding travel region.
As a specific example in the means, the corrected base value in the method of detecting pinching of an object in the power window device of the present invention is found only when the rate of change of a corresponding travel region exceeds a prescribed value, and 1xc2x10.15 is preferably selected as the prescribed value.
According to these means, when the corrected base value is to be set for each of the travel regions, the base median value set for each travel region is multiplied by the correction coefficient set for each travel region, the corrected base value is found by adding the base tolerance value to the multiplied value, and the found corrected base value is set as the corrected base value of the middle point of each travel region as well as a corrected base line is set by connecting the corrected base value of the middle point of each travel region to the corrected base values set to the middle points of adjacent travel regions. Then, when the window sequentially travels in the respective travel regions, the corrected base line set in a travel region is utilized as a corrected base value to be compared with the motor torque value detected in the travel region. Accordingly, the corrected base values set to the respective travel regions do not have a given value but they are set to change along the corrected base line, which permits the corrected base values to be set in accordance with the change of the motor torque values in the respective travel regions. As a result, the occurrence of an object pinched in the window can be detected with high accuracy.